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CSS1 properties
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| Notation for property values
In the text below, the allowed values for each property are listed with a syntax like the following:
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Length units Units
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| The format of a length value is an optional sign character ('+' or '-', with '+' being the default) immediately followed by a number (with or without a decimal point) immediately followed by a unit identifier (a two-letter abbreviation). |
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Pseudo-classes and pseudo-elements
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| In CSS1, style is normally attached to an element based on its position in the document structure. This simple model is sufficient for a wide variety of styles, but doesn't cover some common effects. The concept of pseudo-classes and pseudo-elements extend addressing in CSS1 to allow external information to influence the formatting process. |
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Font properties
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| Setting font properties will be among the most common uses of style sheets. Unfortunately, there exists no well-defined and universally accepted taxonomy for classifying fonts, and terms that apply to one font family may not be appropriate for others. E.g. 'italic' is commonly used to label slanted text, but slanted text may also be labeled as being Oblique, Slanted, Incline, Cursive or Kursiv. Therefore it is not a simple problem to map typical font selection properties to a specific font |
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Formatting model
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| CSS1 assumes a simple box-oriented formatting model where each formatted element results in one or more rectangular boxes. (Elements that have a 'display' value of 'none' are not formatted and will therefore not result in a box.) All boxes have a core content area with optional surrounding padding, border and margin areas |
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Box properties
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| The margin properties set the margin of an element. The 'margin' property sets the margin for all four sides while the other margin properties only set their respective side.
The padding properties describe how much space to insert between the border and the content (e.g., text or image). The 'padding' property sets the padding for all four sides while the other padding properties only set their respective side.
The border properties set the borders of an element. Each element has four borders, one on each side, that are defined by their width, color and style.
The 'width' and 'height' properties set the size of the box, and the 'float' and 'clear' properties can alter the position of elements.
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Basic concepts
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| Designing simple style sheets is easy. One needs only to know a little HTML and some basic desktop publishing terminology. |
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Classification properties
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| These properties classify elements into categories more than they set specific visual parameters.
The list-style properties describe how list items (i.e. elements with a 'display' value of 'list-item') are formatted. The list-style properties can be set on any element, and it will inherit normally down the tree. However, they will only be have effect on elements with a 'display' value of 'list-item'. In HTML this is typically the case for the 'LI' element.
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Text properties
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| The length unit indicates an addition to the default space between words. Values can be negative, but there may be implementation-specific limits. The UA is free to select the exact spacing algorithm. The word spacing may also be influenced by justification (which is a value of the 'text-align' property) |
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The cascade
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| In CSS, more than one style sheet can influence the presentation simultaneously. There are two main reasons for this feature: modularity and author/reader balance. |
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CSS1 conformance
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| A User Agent that uses CSS1 to display documents conforms to the CSS1 specification if it:
attempts to fetch all referenced style sheets and parse them according to this specification
sorts the declarations according to the cascading order
implements the CSS1 functionality within the constraints of the presentation medium |
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Color and background properties
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| These properties describe the color (often called foreground color) and background of an element (i.e. the surface onto which the content is rendered). One can set a background color and/or a background image. The position of the image, if/how it is repeated, and whether it is fixed or scrolled relative to the canvas can also be set |
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